title: Magnetism of nanocrystalline (La(0.5)Sr(0.5))TiO3 doped with 3d cations.
abstract: Nanocrystallites of nominal composition (La(0.5)Sr(0.5))TiO(3) 12-15 nm in diameter exhibit a diamagnetic susceptibility that is greater by a factor of three than that of bulk ceramic material, due to a much-reduced Pauli paramagnetic contribution associated with oxidation (cation deficiency) of the material. Doping the nanocrystallites with 1.5 or 2.0% of every transition metal from V-Ni adds a Curie term to the susceptibility. Exchange coupling between these paramagnetic ions is very weak. In the cases of Fe, Co and Ni there is an additional hysteretic ferromagnetic magnetization, with a moment equivalent to a few tenths of a Bohr magneton per dopant atom, which is attributed to a secondary ferromagnetic impurity phase. Mössbauer analysis of samples prepared with (57)Fe reveals the presence of some metallic iron. Metallic nickel is detected by x-ray diffraction, but no direct evidence of metallic cobalt was found in the ferromagnetic Co-doped material. The possibility of high temperature defect-related ferromagnetism in a metallic oxide is discussed.
authors.affiliation: CRANN and School of Physics, Trinity College, Dublin 2, Republic of Ireland.
authors.forename: Kwanruthai
authors.initials: K
authors.lastname: Wongsaprom
authors.forename: M
authors.initials: M
authors.lastname: Venkatesan
authors.forename: Santi
authors.initials: S
authors.lastname: Maensiri
authors.forename: J M D
authors.initials: JM
authors.lastname: Coey